Icy weekend across much of US

A worker from Wilson Air Center de-ices a Southwest Airlines plane before it lifts off towards Orlando, Fla. Friday, Dec. 6, 2013, at the Memphis International Airport in Memphis, Tenn. National Weather Service said winter storm warnings and watches and an ice storm warning were in effect for northern Mississippi and West Tennessee on Friday. (AP Photo/The Commercial Appeal, Mark Weber)

A pedestrian walks down a street as a flock of birds fly by after heavy snowfall moved through the region on Dec. 6, 2013, in Carbondale, Ill. (AP Photo/The Southern, Steve Matzker)

How cold was it here? A frozen fountain at Chandler's Cove tells the tale at South Lake Union, Friday, Dec. 6, 2013, in Seattle. A big chunk of the U.S. is getting a blast of frigid temperatures, sleet, snow and ice. (AP Photo/ The Seattle Times, Ken Lambert)

A pedestrian walks down the street after heavy snowfall moved through the region on Dec. 6, 2013 in Carbondale, Ill. A big chunk of the U.S. is getting a blast of frigid temperatures, sleet, snow and ice. (AP Photo/The Southern Illinoisan, Steve Matzker)

Snow falls as Gracie McGhee looks out the window as she waits for her ride on Dec. 6, 2013 in Carbondale, Ill. (AP Photo/The Southern Illinoisan, Steve Matzker)